From the early days of Pasteur and Lister, the relationship between infectious organisms and contamination has been well known. There have been many attempts to sterilize or purify environments to prevent contamination of people, food, and articles, otherwise clean from infection, by airborne bacteria, fungi and viruses. There have been many approaches to providing clean, sterile atmospheres.
Systems for delivering aseptic air to and over patients in hospitals are suggested by U.S. Pat. Nos. 3,294,480 and 3,239,305, each invented by Potapenko, U.S. Pat. No. 3,267,955 to Logan et al, and U.S. Pat. No. 3,721,067 to Agnew. Another improvement in hospital room arrangements is suggested in U.S. Pat. No. 3,158,457 to Whitfield which suggests the circulation of large amounts of air.
Another approach to the collection and removal of airborne bacteria, viruses, fungi, and the like from environments is illustrated and described in U.S. Pat. No. 2,825,102 to Hicks et al in which an electric field in an air flow path is used to direct airborne particles to an incinerator.
There are many patents and publications directed to air purification processes in which the air is merely drawn over or subjected to a germicidal agent of one type or another. Examples of such types of processes include U.S. Pat. No. 3,340,680 to Fields et al which is directed to the removal of bacteria and viruses from air by subjecting the air with a small but effective quantity of a polymeric hydrophilic polyelectrolyte. Similarly, in the U.S. Pat. No. 3,433,578 there is disclosed the process of purifying air by washing it with a mixture of water, polyhydroxy alcohol, and glycol ether. Another patent exemplary of this type of approach is U.S. Pat. No. 3,385,654 to Yardney et al in which the contaminated air is contacted by an antimicrobial metal compound which is the silver salt of a lower fatty acid. Other examples of germicidal compositions in the prior art include glycols, ozone, hydrogen peroxide, potassium permanganate, carbon bisulfide, naptha, benzene, and oil of eucalyptus. These compositions may be utilized either as a vapor or as a wash.
One final approach is shown and described in U.S. Pat. No. 4,035,451 to Tringali which is directed to a cartridge type system which induces an air flow past a germicidal product capable of being vaporized. The cartridge includes a hollow, apertured container with a fan therein, a battery for driving the fan, and a support for a strip material having a convoluted configuration mounted in the container. A quantity of germicidal product is impregnated in the strip material.
While all of the above types of devices and compositions may be effective to a certain extent, all of them also suffer certain disadvantages. For example, the large laminar-flow type air changing systems require extensive air treatment equipment. Also, the compositions alone are effective against an air stream passing thereover or therethrough; however, the germicidal agent must be continuously changed with the result that the use thereof is relatively expensive and troublesome. Additionally, where a contaminated air stream is passed over or through a germicidal agent, airborne particles still manage to pass through the treatment and get back into and contaminate the controlled environment. The cartridge of Tringali may be effective but only to a very minimum extent, it is very slow in changing the air of a room, and it requires direct contact between the air and the strip material into which the germicidal product is impregnated to be effective.